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I don't think I ever noticed a site with dark mode, can you give an example?
– AndersFeb 28 at 8:29

Are style guides not flexible enough to accommodate this? I have seen many branding and style guides (for digital applications) take this into consideration right from the beginning, especially if they are going to spend lots of time and money on branding.
– Michael Lai♦Feb 28 at 21:28

@MichaelLai - I know for a fact that the company I'm currently working for wouldn't even begin to entertain this idea. I doubt that Verizon; or Chase; or Bed, Bath and Beyond would give this a second's notice either.
– MayoFeb 28 at 21:35

There is no definitive answer to this question. Some people like dark modes and shades of black, but some prefer the comfort of a traditional color layout. Also, this question can be a topic of a never ending debate, because each person may perceive this based on his personal opinion regarding the color schemes.

Notably, Gmail, Yahoo, and most of the mail based websites have an option for custom themes. This gives the power of the choice to the user, in such a way that he/she may customize their inbox or view the way the want it. This is a brilliant move, in terms of giving the user a personalized feeling.

Also, it is interesting to know that themes mostly are used in applications, rather than websites. This is because we often tend to spend a larger amount of time on applications, rather than websites, especially with the rise of usage of smartphones.

As far as websites are concerned, they often have a theme which is aligned to their brand and identity. Facebook is one such an example. People practically spend hours on the world's most popular social media channel. But they don't have a dark theme. In spite of multiple UI/ UX changes to the website, they do not stray away from their primary color theme of blue and white.

So this is always an arguable topic. But as far as facts go, applications tend to have light/ dark theme, rather than websites. And for websites like YouTube, I think they brought in the light/ dark theme, so that users can align to the themes they've set and gotten used to in their own YouTube mobile application.

How likely are users to activate “dark mode” on their web browsers or operating system?

How likely are users to appreciate the ability to customize the color theme of software they use?

If the people using your website are likely to set their web browser or operating system to dark mode (an increasingly common option), then a compatible design is essential. Often “dark mode” is implemented by inverting colors (so white becomes black, etc.). Color inversion can destroy the usability of photos and videos. At minimum, your site can detect if “dark mode” is active then handle photos and videos correctly.

If your users are interested in being able to “theme” your website, then you could go the additional steps to provide theming features. Most commonly, theming is seen in text-heavy programs like integrated development environments (IDE) or text editors.

If your users are unlikely to work in “dark mode” and don’t appreciate the ability to customize the theme of their software, then you may not need to worry about dark mode.

To reinforce: web sites should just work with a browser's 'dark mode', or user browser preferences in general, rather than trying to micromanage them with their own custom functionality.
– kbelderMar 8 at 18:31

One reason I like dark modes is when on mobile - specifically for battery life. Does it actually make a difference? I don't know the answer to that, but I spend so much of my browsing time on text-heavy news sites that almost always have a white background that I feel like it should make some difference! That said, I can only think of one that is dark that I regularly go to: ars technica

Only on OLED displays. On any other kind of display the individual pixels don't emit light, they block light emitted by the backlight to create the different colours (or black). Even if the screen is mostly black. the backlight still has to be on just the same for the few bright pixels.
– tylisirnMar 3 at 9:33

I have a Pixel 3, so I guess that's good for me!
– Warren PayneMar 5 at 18:25

However, if we do not call it dark mode, but high contrast mode, then it makes sense regarding a website's inclusive design, its' accessibility. Therefore, I would recommend this kind of mode for many public sites.

This used to be a major consideration for sites and software however with the improvement of web browsers, designing and building a dark mode are no longer a necessity as the modern browsers provide options for one that will be, in most cases, better and better align with the needs of the users